Advancement of portable telephones is accelerating. A portable telephone is able to access a server on the Internet to download a variety of contents and applications. Such applications that are downloaded from a network and used include, for example, an application called “Java Applet” written in the Java (registered trademark) programming language.
Open networks, including the Internet, generally have poor security, and hence, Java Applets distributed through such an open network are not necessarily reliable.
Accordingly, it is necessary to exclude access to networks established by an illegal Java Applet. To meet this demand, an access limiting technique called the “sandbox model” has been proposed. The sandbox model allows communication terminals, which act as clients, only to access a server from which a Java Applet is downloaded.
However, network resources will potentially be further integrated or distributed in the future. In such situations, the existing access limiting technique mentioned above may be inadequate.